Locating and fastening means



i 1943- F. w. MEREDITH 2,324,224

LOCA TING AND FASTENING MEANS Filed May 51, 1941 2 Sheets-Sheet 2 .J"' W A 4W 3 25 25 Am, QL MWAZL...

Patented July 13, 1943 UNlTED STATES PATENT OFFICE LOCATING AND FASTENING MEANS Application May 31, 1941, Serial No. 396,130 In Great Britain May 16, 1940 3 Claims.

For locating and fastening interchangeable members it is usual to employ fixing bolts or studs and/or locating pins on one member and correspondingly positioned holes in another member to receive the bolts, studs or pins. For properly positioning the members with respect to one another some of the bolts or the like must be accurately positioned and also an accurate fit in the holes receiving them, and where one member is to be replaceable by another similar member the necessary accuracy is difficult to obtain in mass production. The object of the invention is to avoid this disadvantage.

According to the invention means for locating and fastening interchangeable members comprises a locating bolt or the like on one member engaging in a properly positioned and accurately fitting hole in the other member and preventing all relative movement except rotation about the axis of this bolt, a second locating bolt or the like on one of the members, spaced laterally from the other locating bolt and engaging in a hole in the other member and accurately fitting this hole transversely of a line joining this hole with the first bolt or hole but with clearance along this line and means clamping the members together with the locating bolts in position in the respective holes.

It is convenient for the locating bolts or the like also to serve as means for clamping the members together, and they may be supplemented by one or more additional fiXing bolts or studs which are loose fits in the holes receiving them so as to require no accuracy as regards the position and size of the bolt and bolt holes.

One application of the invention is to the mounting of automatically controlled servo -motor units in aircraft or watercraft. Such units are of intricate construction and if a unit fails it is convenient to replace it by another similar unit rather than to attempt to repair the unit while fitted in the craft. It is necessary, however, that the replacement unit should be accurately located with respect to the craft if it is to be coupled up without adjustment to the existing connections. The invention therefore further comprises, in an aircraft or watercraft, locating and fastening means as aforesaid for the attachment of an interchangeable servo-motor unit to another member consisting of a mounting for the servo-motor unit in the craft.

One specific application of the invention to the mounting of a servo-motor unit is shown by way of example in the accompanying drawings, in which:

Figure 1 is a plan, partly in section, of the servo-motor unit and its mounting, the section being taken on line Il of Figure 2,

Figure 2 is a side elevation of the servo-motor unit and mounting shown in Figure 1,

Figure 3 is a section on line 3-3 of Figure 1,

Figure 4 is a section on line 4-4 of Figure l, and

Figure 5 is a section on line 55 of Figure 1.

Referring to the drawings, a base member Hi fixed in the craft to receive the servo-motor unit is provided with three upstanding studs H, l2 and I3 spaced apart. These studs are preferably so arranged as to occupy the corners of approximately an equilateral triangle. The servomotor unit comprises a triangular frame 14 carrying a servo-motor 15 which is connected to a lever 16. This lever is carried at one end by a pivot I! mounted in an extension l8 of the frame M. The other end of the lever l6 has a connection IQ for the part to be operated by the servo-motor.

The frame M has holes 20 to receive the studs ll, [2 and iii. In the hole to receive the stud ll there are non-rotatable liners 2| accurately fitting the stud II. In the hole 20 receiving the stud l2 there are non-rotatable liners 22 each formed with a slot 23 extending in the direction of the hole 20 which receives the stud I l and having a width equal to the diameter of the stud l2. The third hole 20 for receiving the stud [3 has non-rotatable liners 24 with central hole 25 of such size as to provide adequate clearance around the stud [3. The studs II, l2 and [3 are screw-threaded at their outer ends to constitute bolts receiving nuts 26 to clamp the frame It on to the base ID.

The stud I I accurately fitting the liners in the frame properly locates the frame on the base at a position close to the pivotal mounting of the lever 16 on the frame. The stud l2 prevent ro tation of the frame M about the stud l l but the slots in the liners in which the stud 12 engages allow for a wide tolerance in the relative positions of the studs II and I2 and the relative positions of the holes 20 in the frame for receiving these studs. The positions of the stud l3 and the hole 20 which it engages need not be accurate owing to the wide all-round clearance. The stud I3 serves only as a means for clamping the frame [4 to the base and the other studs H and I2 also serve for clamping purposes in addition to locating the frame M in position.

It will be seen therefore that the only accuracy required in the forming of the holes in the frame is in regard to the size and position of the hole to receive the stud l I and the width and direction of the slots receiving the stud I2. As the frame It is accurately located by the stud H, which is close to the pivot of the operating lever l6, and is accurately positioned rotationally with respect to this stud by the stud I2, the servo-motor unit can be replaced by another similar unit without any necessity for adjustment of the connection IS with other mechanism in the craft.

I claim:

1. In an aircraft or watercraft the combination with a mounting for a servomotor unit and an interchangeable servomotor unit carried by said mounting, of a locating bolt projecting from said mounting and engaging in a properly positioned and accurately fitting hole in said servomotor unit and. preventing movement of the servomotor unit on the mounting except rotation about said belt, a second locating bolt projecting from the mounting spaced laterally from the first said locating bolt and engaging in a slot in said servomotor unit, said slot extending in line with said hole so as to provide clearance for said second locating bolt along said line and said slot having a width accurately fitting said second 10- cating bolt so as to prevent rotation of said servomotor unit about the first said locating bolt, a third bolt projecting from said mounting and spaced from the other locating bolts and engaging in a hole in the servomotor unit with appreciable clearance, and means comprising said bolts for clamping the servomotor unit on the mountmg.

2. Locating and fastening means for interchangeable members comprising a locating part on one member engaged in a properly positioned and accurately fitting hole in the other member and preventing all relative movement of said members except rotation about the axis of said part, a second locating part on one of said members spaced laterally from the first said locating part and engaging in a hole in the other member and accurately fitting this hole transversely of a line joining said holes, but having clearance along the said line, a third part on one of said members arranged to extend loosely through a hole in the other member, which members are provided with abutting faces in the region of each of said parts so as to provide a three-point support and means clamping the abutting faces together with said locating parts in position in the respective holes.

3. In an aircraft or watercraft the combination with interchangeable members consisting of a mounting for a servomotor unit and an interchangeable servomotor unit carried by said mounting, of a locating bolt in one member engaging in a properly positioned and accurately fitting hole in the other member and preventing all relative movement of said members except rotation about the axis of said locating bolt, a second locating bolt in one of said members spaced laterally from the first said locating bolt and engaging in a hole in the other member and accurately fitting this hole transversely of a line joining said holes but having clearance along said line, a third bolt on one of said members, arranged to extend loosely through a hole in the other member, which members are provided with abutting faces adjacent said bolts so as to provide a three-point support and means comprising said bolts for clamping said members together across said abutting faces.

FREDERICK WILLIAM MEREDITH. 

